Yes.
But on the other hand, when we discuss Christianity, what are the main divisions? Protestant and Catholic. As a practical accounting runs, it's more or less split 60-50% Catholic and then everybody else. The division is further cut down by the fact a number of prominent Protestant sects like the Lutherans no longer have significant distinctions in doctrine from Catholicism. In practical terms, one could present mass to 70% of Christianity at once and not upset somebody.
Islam can be divided into at least three major sects at the moment, of which two are directly inimical to each other, and their split is rather more even. So yes, I think it's safe to say Christianity has homogenized better.
I'd add Eastern Orthodox to that, so there are three biggies in Christianity. But even before we consider the ones that don't fall under any of those, these three are staggeringly fractured. Protestants range from Congregationalists, who are arguably one step away from Unitarian Universalists, to Lutheranism, which, as you mentioned, is as tightassed as Catholicism, and everything in between. Catholicism splits into the Eastern and Western rites, and additionally is subject to widely varying interpretation from region to region. (Catholicism in Latin America, for instance, makes its U.S. counterparts look downright progressive.)
And Eastern Orthodoxy, I mean... holy ****. First, you have the schism between the Eastern Orthodox Church "proper" versus the Non-Chalcedonian Orthodox communion, plus within each of these groups you have autocephalous churches, autonomous churches, and churches not recognized by their respective communions.
Then, outside these three vague semblances of unified groups, you have the Anglicans, who also range from progressive to conservative, and the various Non-Trinitarian sects like Oneness Pentecostals, Jehova's Witnesses, "free" non-denominational Christians, etc., and the so-called Assyrian Church, which itself spawned an offshoot.
So yeah, it's a mess. My point is that although we can divide both these religions into broad categories, quite often those categories don't actually tell us very much.